Representative Jim Banks, a staunch conservative with the backing of a deep-pocketed political action committee, opened his bid for an Indiana Senate seat on Tuesday with an ad highlighting his deployment to Afghanistan and issuing a broadside against “radical socialist Democrats.”
Mike Braun, who currently holds the seat and is one of the state’s two Republican senators, will run for governor next year, creating an opening that could lead to a crowded primary fight in the reliably Republican state. Mr. Banks, who recently headed the House’s Republican Study Committee, a conservative caucus that is broader and less confrontational than the House’s Freedom Caucus, turned to the Senate after he lost his bid to be whip, the No. 3 Republican position in the G.O.P.’s new House majority.
He enters the contest with the backing of the Club for Growth, a moneyed conservative political action committee that spent millions of dollars to get its preferred House and Senate candidates across the line in the November midterms. The group and its super PAC “are prepared to spend whatever it takes to help Banks secure the nomination and victory,” its president, David McIntosh, said Tuesday.
Club for Growth is already spending money against another possible candidate, the former Indiana governor Mitch Daniels, whom it considers too conciliatory. Mr. Banks also has the endorsement of Representative Larry Bucshon, another Indiana Republican, and Senator Tom Cotton, Republican of Arkansas.
But Indiana’s current governor, Eric Holcomb, who is facing a term limit, is considering a run for the Senate, as is Representative Victoria Spartz, whose Ukrainian birth has elevated her voice in Congress.
In his announcement, Mr. Banks called himself “a small-town kid from a working-class home” with deep roots in Indiana and a record fighting overseas and in Congress for “conservative Hoosier values.” He threw in a nod to former President Donald J. Trump, calling him “the strongest president in my lifetime.”
Mr. Braun, a businessman who had little political experience when he ran against Senator Joe Donnelly, a Democrat, in 2018, beat him by six percentage points. His victory came two years after Representative Todd Young whipped Evan Bayh, a Democrat and former senator who had come out of retirement to try a comeback. Those defeats signaled just how difficult a Democratic comeback in the state would be.
In November, Mr. Young won re-election with nearly 59 percent of the vote.